Double reflector type microphone



Get. 15, 1935.

o. 51 HANSON DOUBLE REFLECTOR TYPE MICROPHONE Filed Marci. 11, 1932 1 iNVENTOR 5 QB HANsON ATTORN EY Patented on. 15, 1935 v r PATENT OFFICE 2.017.122 DOUBLE nnrmc'roit ms MICROPHONE Oscar B. Hanson, Westp'ort, Conn, assignor to Radio Corporation of America, a corporation of ware Application March n, 1932, Serial No. 598,104

1 Claims. (01. 119-4) This invention relates to a sound reflecting microphone, and more particularly the type employing double reflecting surfaces such as are used in radio broadcasting.

5 An object of this inventionis to simplify and improve sound reflecting microphones utilizing double reflecting surfaces.

Another object of this invention is to provide a. double sound reflecting microphone which is 10 mounted on a portable stand and may be used in or out of doors, such as in a theater, studio, baseball park, or the like.

Another object of this invention is to collect and doubly reflect sound waves in a manner that 5 improves and increases theemciency of the microphone.

A feature of this invention is the novel means of adjustment provided for one of the reflectors to move in or out of focus, thus obtaining sharp 20 focus and a narrow beam of pick-up, or soft focus with a wide beam of pick-up.

Another feature of this invention resides in the new and novel absorbing and shield elements which are placed directly in front of the micro- 25 phone to absorb or attenuate any undesirable 4 30 the microphone were only those received or col-- lected by the single reflector whereas with the double reflector of my invention there is, in addition to the reflected sound, such other desirable sounds as will arrive at the microphone directly.

5 These other desirable sounds are mixed and blended with the reflected sounds, and result in more pleasing and increased efliciency of sounds entering or energizing the microphone. These reflected sounds arrive at the microphone at a small angle. Therefore, there ll be little discrimination between the higher frequencies due to the angular characteristics of the microphone.

The new advantage being a superior response to the higher audio frequencies over that obtainable 45 with practical single reflector type. Likewise,

previous reflectors of the single reflector type were also dependent to some extent on the size or diameter of the reflector for adequate low frequency response in the order of 50 to 100 50 cycles. Whereas, in my invention of the double reflector type microphone, the reduction in diameter of the large reflector will not discriminate so appreciably against the low frequencies. The

low frequency response of the microphoneis en- 55 hanced and increased by the action of the large reflector as a baflle. This effect is well known to persons skilled in the art.

The characteristics of the reflecting surfaces in general indicate that the low frequencies are 60 obtained largely by sound waves directly affecting .the microphone diaphragm, whereas the high frequencies are obtained and reproduced'by the two reflecting surfaces. Should it be desirable to change the characteristics of the double reflector or to eliminate any undesirable sounds 5 such as those of the low frequencies, 1. have de vised new and novel adjustable absorbing and attenuating shield elements. The double sound reflector microphone consists essentially of a relatively large reflector. in the center of which is mounted a microphone facing a smaller reflector located coaxially with the microphone and removed from it by the proper distance. Thelarge reflector is so shaped that sounds, from the proper direction, impinging on its surface, are directed toward the small reflector which reflects them to the microphone. In addition to this re flected sound, the microphone also collects sounds reaching it directly, thus resulting in an increase in emciency of the microphone.

In the drawing, like references refer to similar parts throughout the several views in which,

Fig. 1 is a vertical cross section, the section being taken on lines l-I of Fig. 2;

Fig. 2 is a front elevation of the improved reflector;

Fig. 3 is a vertical cross section of the absorbing and attenuating shield elements;

Fig. 4 is a front elevation of the absorbing and attenuating shield elements.

The invention is best shown and illustrated in Figs. 1 and 2 wherein the large reflector I, which is approximately three feet in diameter and is composed of Bacon impregnated fabric, or any other suitable sound reflecting material, is shown 3 mounted upon a suitable pivoted and portable supporting member 2 which is pivoted at the center of the large reflector i by means of bolts 3, and wing nuts 4. The small or second reflector 5 is approximately 4" in diameter and is composed 40 of polished walnut wood, or may be of any other 7 good sound reflecting material. This reflectin surface 5 is supported by a metallic ring 6 which has four round-rods I mounted thereon. These rods 1 are supported on and pass. through a larger metallic ring 8 with suiflcient clearance between the rods 1 and the holes in the metallic ring 0 to permit movement of thesecond reflector to andfrom the large reflector, and terminate at a binding ring 9. The smalleradiustable reflector 5 together with its associated parts are'supported to the large reflecting surface i by four rigid metallic rods II. The microphone M is a standard condenser type microphone mounted in a suitable aperture II in the large reflector l in any convenient manner not shown. As the microphone alone forms no part of my invention, no further description is believed tobe necessary.

Referring now to Figs. 3 and 4, the adjustable completely absorb and prevent transmission of undesirable sounds, an adjustable telescoping shield 22 is provided. This complete assembly of absorbent rings and shields is then mounted on and secured to the large reflector I by means of four nuts I9, 20, 2|, and HA.

In the operation of this improved microphone and reflector, also by referring to the drawings mentioned above, it will be seen that sound waves impinging on the large reflector l in a direction parallel to its axis will be reflected to the smaller reflector 5 and then reflected to the microphone. It will also be seen that sounds arriving at comparatively small angles with respect to the reflector axis, will reach the microphone diaphragm 7 directly. When this double reflector is used in the studio, auditorium, or out doors, an operator sets the microphone together with its associated reflecting surfaces at any convenient location, and directs the center of the reflector toward the spotfrom which'it is desired to collect the most desirable sound waves. To further improve the sound qualities, the operator properly focusses the sounds energizing the microphone by moving in or out the small reflecting surface 5 by adjusting the ring 9 until the proper reflected sound is obtained, and to properly absorb undesirable sounds from entering at an angle with respect to the reflector axis, a varying number of absorbing rings I! are inserted and the resulting telescoping shield is thus correspondingly increased or decreased in length.

It will be seen by the dot and dash lines indicated by the arrows at A, Fig. 1, that the sound waves follow a direction parallel to the axis of the smaller reflector 5, and is then reflected to the microphone M. It will also be seen that sounds arriving at an angle in respect to the axis of the reflector as indicated by the arrows B, will reach the microphone directly. Any other sounds reaching the inside of the large reflector I from the sides will be either substantially eliminated or properly attenuated before reaching the microphone by selecting the proper amount of absorbing rings and correct length of shield as mentioned above.

Although this invention has been described, and illustrated, it is apparent that the size, shape and separation of the two reflectors and materials of construction may be varied in order to obtain the desired result and yet retain the fundamental principles of this device within the spirit and scope of the appended claims.

I claim:

1. In combination, a directive sound receptive z :microphone, a large parabolic reflecting surface sounds, said microphone being mounted on said large reflector. 7

2. In combination, a directive sound responsive system comprising a condenser type. microphone mounted upon a first reflector with a concave 5 parabolic reflecting surface, an adjustable sound absorbing means interposed between the microphone and a second reflector with a convex reflecting surface, the said second reflector being mounted to slide upon a support fastened to the first reflector to adjust the focus of soundsentering or energizing the said microphone, the sound absorbing means comprising a plurality of fibre rings which are arranged to permit properly reflected sound from the second reflector to 15 energize or enter the said microphone.

3. A sound responsive device comprising a microphone mounted upon the rear of a concave sound reflecting surface, a 'convexsound reflecting surface, said convex sound reflecting surface. 20 being adjustable with respect to said microphone, and sound absorbing means comprising a plurality of rings interposed between the said convex sound reflecting surface and said microphone.

4. A sound responsive device comprising a microphone mounted upon the rear of a concave sound reflecting surface, a convex sound reflecting surface, said convex sound reflecting surface being adjustable with respect to said microphone, and sound absorbing means comprising 30 a plurality of adjustable sound absorbing ring elements forming a funnel-like opening interposed between the said convex sound reflecting surface and said microphone.

5. A directive sound receptive microphone 35 comprising a condenser type microphone mounted upon the rear of a concave sound reflecting surface, a convex sound reflecting surface, said convex sound reflecting surface being adjustable with respect to said microphone by means of a plurality of rods passing through a support ring which is secured to the concave sound reflecting surface, and sound absorbing means comprising.

a plurality of rings forming a funnel-likeopening interposed between-the said convex sound re- 45 flecting surface and the microphone.

6. In combination, a directive sound responsive system comprising a microphone mounted upon a flrst reflector with a concave parabolic reflecting surface, an adjustable sound-absorbing means infocus of sounds entering or energizing the microphone, the sound-absorbing means comprising 'a plurality of rings arranged to permit properly reflected sound from the second reflector to energize or enter the said microphone.

Y 7. A directive sound receptive microphone comprising a microphone mounted upon the rear of a concave sound reflecting surface, a convex sound reflecting surface, said convex sound reflecting surface being adjustable with respect to said microphone by means of a plurality of rods passing through a support ring which is secured to the concave sound reflecting surface, and sound absorbing means comprising a plurality of rings forming a funnel-like opening interposed between the said convex sound reflecting surface and the microphone.

' OSCAR B. HANSON. 

